I would have suggested Moon+ as well but I see that you are already happy with it.
I'm really happy with my nexus 7 and moon+ as well. If you do decide to get calibre ccompanion I'm interested in what you think about it - the file transfer thing with moon+ bugs me as well but yet not enough to get another app.
It seems strange to me that you can't access the nexus 7 via your Mac. I use Windows so I don't know if this is to be expected, but you might want to check if you have the correct drivers installed or if you can download them from somewhere?